CTD and Water Sampler

A water sampler with a CTD probe is being deployed from the research vessel Polarstern. (Photo: Agnieszka Beszczynska) (Photo: Alfred-Wegener-Institut)

The CTD is an oceanographic instrument used to determine electrical conductivity, temperature, and water depth.

Salinity is calculated from conductivity while taking temperature and pressure into account.

CTD probes are deployed into the water column from research vessels using cables, with measurement data either transmitted to the vessel in real-time or stored internally.

The CTD probe is usually equipped with additional sensors that measure parameters such as oxygen content, chlorophyll concentration, or water turbidity.

By combining these measuring instruments with a water sampler, scientists can collect samples from different depths. The data and samples can be used to create a so-called "profile" of the water column.

Abb. 2: The CTD on the working deck (Foto: Agnieszka Beszczynska) (Photo: Alfred-Wegener-Institut)
Fig. 3: The CTD is picked up by the ship's crane (Foto: Agnieszka Beszczynska) (Photo: Alfred-Wegener-Institut)
Fig. 4: The CTD is about to be lowered into the water. (Foto: Agnieszka Beszczynska) (Photo: Alfred-Wegener-Institut)